Medicare Part B is funded by a combination of payroll taxes, general tax revenue, and monthly premiums from people enrolled in the program

Medicare Part B covers doctor visits, outpatient care, and medical equipment. The money to pay for these services comes from three sources: taxes taken from workers' paychecks while they are still working, money from the federal government's general budget, and monthly premiums that people on Medicare pay themselves. The balance between these three sources shifts slightly each year based on how many people are enrolled and how much medical care costs.

Understanding where the funding comes from matters because it affects what you pay and what changes might happen to the program in the future. It also helps explain why your Part B premium can increase from year to year.

Key Takeaways

  • Part B is funded by payroll taxes (2.9% of wages, split between employer and employee), general federal tax revenue, and monthly premiums paid by people enrolled in Part B.
  • Payroll taxes collected today fund current benefits for today's retirees, not a personal savings account for your future retirement.
  • Your monthly Part B premium covers roughly 25% of the program's costs; the other 75% comes from taxes and general revenue.
  • Part B premiums increase each year based on program costs and inflation, and the increase is announced in the fall for the following year.

How Payroll Taxes Fund Part B

When you work, your employer and you each pay a Medicare tax of 1.45% on your wages — that is 2.9% total. This tax is separate from Social Security tax and income tax. These payroll taxes go into the Medicare Hospital Insurance Trust Fund, which primarily pays for Part A (hospital care), but the system is interconnected: money collected from workers helps support the overall Medicare structure that Part B operates within.

The payroll tax system is pay-as-you-go, meaning taxes collected from today's workers pay for today's retirees' care, not for a personal account set aside for your own future benefits. This is why the ratio of workers to retirees matters to the program's long-term funding. If you are self-employed, you pay the full 2.9% yourself.

If your income is above a certain threshold, you may pay an additional 0.9% Medicare tax. For 2024, this applies to single filers earning over $200,000 and married couples filing jointly earning over $250,000, though these thresholds do not adjust for inflation each year.

General Federal Revenue and the 75% Government Share

Part B is unusual among Medicare parts because the federal government covers roughly 75% of its costs through general tax revenue — money from income taxes, corporate taxes, and other federal sources. This is different from Part A, which is funded primarily through payroll taxes alone. Because of this large government contribution, Part B premiums do not have to cover the full cost of the services.

This 75/25 split is set by law and has been in place since Medicare began in 1965. It means that even if you never paid a dime in Medicare taxes, you still receive substantial government funding for your Part B benefits once you turn 65 and enroll. The government's share is why Part B premiums have remained lower than they would be if enrollees had to pay the full cost themselves.

Monthly Premiums: What You Pay Out of Pocket

Your monthly Part B premium is the amount you see deducted from your Social Security check or billed directly. This premium covers roughly 25% of Part B's total costs. The remaining 75% comes from the federal government's general revenue. In 2024, the standard Part B premium was $164.90 per month for most people, though higher-income enrollees pay more through Income-Related Monthly Adjustment Amounts (IRMAA).

Your premium is not fixed. It changes each year based on two main factors: the rising cost of medical services and the number of people enrolled in Part B. The Centers for Medicare & Medicaid Services (CMS) announces the new premium amount each fall, and it takes effect the following January. Some years the increase is small; other years it is larger.

If you delay enrolling in Part B after you first become may be able to access at 65, you may face a permanent penalty on your premium. The penalty is 10% for each full year you could have enrolled but did not. This penalty applies for as long as you have Part B, so enrolling on time is important even if you do not plan to use it when ready.

Income-Related Premiums for Higher Earners

If your income is above a certain level, you pay a higher Part B premium through IRMAA. CMS uses your tax return from two years prior to determine your income level. For 2024, single filers with income over $97,000 and married couples filing jointly with income over $194,000 paid higher premiums, with the amount increasing in tiers as income rises.

These higher premiums still come from the same funding sources — payroll taxes, general revenue, and your out-of-pocket payment — but you are straightforward paying a larger share of the cost yourself. If your income drops significantly due to retirement, job loss, or other life changes, you can request that CMS recalculate your IRMAA using your current year's income instead of the two-year-old tax return.

How Part B Costs Are Controlled

Medicare Part B has built-in mechanisms to manage costs. Doctors and providers who accept Medicare must accept the Medicare-approved amount as payment in full for most services. This means they cannot bill you extra beyond what Medicare allows, even if they charge other patients more. This is called accepting assignment.

You also pay a deductible and coinsurance for Part B services. In 2024, the Part B deductible was $240 per year. After you meet the deductible, you typically pay 20% of the Medicare-approved amount for most services, and Medicare pays 80%. These out-of-pocket costs are another way the program keeps total spending in check — they give enrollees a reason to use services thoughtfully.

What Happens If Part B Funding Changes

Congress can change how Part B is funded, but it rarely does. Any major change would require new legislation. Some proposals over the years have suggested raising the payroll tax rate, increasing the premium percentage that enrollees pay, or adjusting income thresholds for IRMAA. None of these changes have been enacted, but they are part of ongoing discussions about Medicare's long-term sustainability.

The program's funding is stable for now, but demographic shifts — more people turning 65 and fewer workers per retiree — will likely prompt discussions about funding adjustments in the coming decades. Staying informed about these conversations can help you plan for your own healthcare costs in retirement.

Frequently Asked Questions

Does my Part B premium go into a personal account for my future care?

No. Your premium, along with payroll taxes and general revenue, goes into a shared pool that pays for all Part B services for all enrollees. The system is pay-as-you-go, so your premium helps pay for current retirees' care, just as today's workers' taxes help pay for yours.

Why does my Part B premium increase every year?

Premiums increase when the cost of medical services rises or when more people enroll in Part B. CMS calculates the new premium each year to may support the program can cover its costs. The increase is announced in the fall and takes effect in January.

Can I reduce my Part B premium if my income drops?

If you are paying a higher premium due to IRMAA and your income has dropped significantly, you can request a recalculation. Contact Social Security or Medicare with proof of your income change, such as a recent tax return or letter from your employer. They will determine whether your premium should be lowered.

What is the difference between Part B funding and Part A funding?

Part A is funded almost entirely by payroll taxes. Part B is funded by payroll taxes, general federal revenue (75%), and enrollee premiums (25%). This is why Part B premiums exist and Part A does not have a separate monthly premium for most people.

If I paid Medicare taxes my whole life, am I may provide Part B coverage?

Paying Medicare taxes makes you may be able to access for Part B at 65, but you must actively enroll. If you delay enrollment without a valid reason, you may face a permanent premium penalty. Enrollment happens through Social Security or Medicare.gov.